Circular saw blade

ABSTRACT

A circular saw blade includes a plurality of cutting teeth repeatedly alternating between a first set of cutting teeth and a second set of cutting teeth around the periphery of the saw blade. Each first set of cutting teeth includes at least two efficient cutting teeth, each second set of cutting teeth comprising at least one robust cutting tooth. Each first set of teeth and each second set of teeth are configured such that, if one tooth in the first set of teeth breaks, the chip load in the immediately following second set of teeth increases by less than approximately 45%.

RELATED APPLICATION

This application claims priority, under 35 U.S.C. § 119(e), to U.S.Provisional Application No. 62/829,106, filed Apr. 4, 2019, which isincorporated by reference.

TECHNICAL FIELD

This application relates to circular saw blades.

BACKGROUND

FIGS. 1-3B show an example of an existing circular saw blade 10. The sawblade 10 includes a generally circular blade body 12 having a first sideface 14 and an opposite second side face 16. A plurality of cuttingtooth holders 18 are coupled to a periphery 20 of the blade body 12.Around the periphery 20 are a plurality of gullets 22, each disposedbetween two adjacent cutting tooth holders 18. Each cutting tooth holder18 supports one of a plurality of cutting teeth 24. Each tooth 24 may begenerally prismatic in shape and has a rake face 26, a relief face 28, acutting edge 30, and a pair of lateral faces 32, 33.

Each rake face 26 faces toward an adjacent gullet 22, extends transverseto the first and second side faces 14, 16, and is disposed at a rakeangle α relative to a radius R of the blade body 12. Each relief face 28extends from the rake face 26 toward the tooth holder 18 that issupporting the cutting tooth 24, extends transverse to the first andsecond side faces 14, 16, and is disposed at a relief angle β relative aline T tangent to a circumference C of the saw blade 10. The cuttingedge 30 is disposed at a junction between the rake face 26 and therelief face 28 and extends transverse to the first and second side faces14, 16. Each relief face 28 is also beveled toward one of the first sideface 14 and the second side face 16 in an alternating top bevel (ATB)pattern at a top bevel angle γ relative to a plane P perpendicular tothe blade body 12. The rake angle α, relief angle β, and top bevel angleγ are the same for all teeth 24 on the saw blade.

In such existing saw blades there is generally a trade-off between life(i.e., number of cuts that can be achieved before blade feels dull orcannot make a cut in a reasonable amount of time or when applying areasonable amount of force) and durability (i.e., how often a tooth onthe blade chips or breaks). Generally, wear life increases anddurability decreases with increases in the rake angle, relief angle,and/or top bevel angle. On the other hand, generally, durabilityincreases and life decreases with decreases in the rake angle, reliefangle, and/or top bevel angle. Therefore, the rake angle, relief angle,and top bevel angle are often selected so as to optimize either life andcutting speed (i.e., for more efficient and faster cutting) ordurability (i.e., for cutting more abusive materials), but not both. Sawblades optimized for more efficient cutting tend to have their teethchip and break when cutting more abusive materials such as wood withnails, which can lead to a cascade of broken teeth and premature failureof the saw blade. Saw blades that are optimized for durability tend todull quickly, requiring more frequent blade changes. Other saw bladesthat attempt to compromise between life and durability tend to performbelow average in both.

SUMMARY

In an aspect, a circular saw blade includes a generally circular bladebody having a first side face and an opposite second side face, aplurality of cutting tooth holders coupled to a periphery of the bladebody, a plurality of gullets, and a plurality of cutting teeth. Eachgullet is disposed between two adjacent cutting tooth holders. Eachcutting tooth is supported by one of the cutting tooth holders and has arake face facing toward an adjacent gullet and extending transverse tothe first and second side faces, a relief face extending from the rakeface toward the tooth holder that is supporting the cutting tooth andextending transverse to the first and second side faces, and a cuttingedge at a junction between the rake face and a relief face and extendingtransverse to the first and second side faces. The cutting teethalternate between at least one first set of cutting teeth and at leastone second set of cutting teeth around the periphery of the blade body.Each first set of cutting teeth includes at least two efficient cuttingteeth, each having the relief face beveled toward one of the first sideface and the second side face in an alternating top bevel (ATB) patternat a first top bevel angle, the rake face disposed at a first rake anglerelative to a radius of the blade body, and the relief face disposed ata first relief angle relative a line tangent to the periphery of theblade body. Each second set of cutting teeth includes at least tworobust cutting teeth, each having the relief faces beveled toward one ofthe first side face and the second side face in an alternating top bevel(ATB) pattern at a second top bevel angle, the rake face disposed at asecond rake angle relative to a radius of the blade body, and the reliefface disposed at a second relief angle relative a line tangent to theperiphery of the blade body. At least two out of the following threeconditions are satisfied: (a) each second bevel angle is less than eachfirst bevel angle; (b) each second rake angle is less than each firstrake angle, and (c) each second relief angle is less than each firstrelief angle.

Implementations of this aspect may include one or more of the followingfeatures. If only two of the three conditions are satisfied, then one ofthe following additional conditions is also satisfied: (a) each secondbevel angle is approximately equal to the first bevel angle; (b) eachsecond rake angle is approximately equal to each first rake angle; and(c) each second relief angle is approximately equal to each first reliefangle. In another implementation all of the three conditions aresatisfied. For example, each second bevel angle may be less than eachfirst bevel angle, each second rake angle may be less than each firstrake angle, and each second relief angle may be approximately equal toeach first relief angle. In another example, each second bevel angle maybe approximately equal to each first bevel angle, each second rake anglemay be less than each first rake angle, and each second relief angle isless than each first relief angle. In yet another example, each secondbevel angle may be less than each first bevel angle, each second rakeangle may be approximately equal to each first rake angle, and eachsecond relief angle may be less than each first relief angle.

Each first rake angle may be from approximately 16° to approximately 22°and each second rake angle may be from approximately 8° to approximately16°. Each first relief angle may be from approximately 16° toapproximately 20° and each second rake angle may from approximately 8°to approximately 14°. Each first top bevel angle may be fromapproximately 16° to approximately 22° and each second top bevel anglemay be from approximately 8° to approximately 14°. Each cutting toothmay include one or more of a carbide, cermet, polycrystalline diamond(PCD) or high speed steel (HSS) cutting insert. The first set of teethand the second set of teeth may be configured so that the second set ofteeth receive a greater percentage of a total chip load on the pluralityof teeth than the first set of teeth. The first set of teeth may receiveapproximately 5% to 35% of the total chip load. The second set of teethmay receive approximately 65% to 95% of the total chip load.

Each second set of teeth may further include a raker tooth. Each rakertooth may have the relief face unbeveled toward the first side face andthe second side face, the rake face disposed at the second rake anglerelative to a radius of the blade body, and the relief face disposed atthe second relief angle relative a line tangent to the periphery of theblade body. Each second set of teeth are arranged in an alternating topbevel plus raker (ATB+R) pattern. The raker tooth may have a heightapproximately equal to a height of each of the beveled teeth in thesecond set of teeth or a height less than a height of each of thebeveled teeth in the second set of teeth. Each first set of teeth andeach second set of teeth immediately following the first set of teeth ina direction opposite a cutting direction of the saw blade may beconfigured such that, if one tooth in the first set of teeth breaks, thechip load in the immediately following second set of teeth increases byless than 45%.

In another aspect, a circular saw blade includes a generally circularblade body having a first side face and an opposite second side face, aplurality of cutting tooth holders coupled to a periphery of the bladebody, a plurality of gullets, and a plurality of teeth. Each gullet isdisposed between two adjacent cutting tooth holders. Each cutting toothis supported by one of the cutting tooth holders and has a rake facefacing toward an adjacent gullet and extending transverse to the firstand second side faces, a relief face extending from the rake face towardthe tooth holder that is supporting the cutting tooth and extendingtransverse to the first and second side faces, and a cutting edge at ajunction between the rake face and a relief face and extendingtransverse to the first and second side faces. The cutting teethalternate between at least one first set of cutting teeth and at leastone second set of cutting teeth around the periphery of the blade body.Each first set of cutting teeth include at least two efficient cuttingteeth. Each second set of cutting teeth comprising at least one robustcutting tooth. The first set of teeth and the second set of teeth areconfigured so that the second set of teeth receive a greater percentageof a total chip load on the plurality of teeth than the first set ofteeth.

Implementations of this aspect may include one or more of the followingfeatures. The first set of teeth may receive approximately 5% to 45% ofthe total chip load. The second set of teeth receive approximately 55%to 95% of the total chip load. Each rake face in each first set ofcutting teeth may be disposed at a first rake angle relative to a radiusof the blade body and each rake face in each second set of cutting teethmay be disposed at a second rake angle relative to a radius of the bladebody, the second rake angle less than the first rake angle. Each firstrake angle may be from approximately 16° to approximately 22° and eachsecond rake angle may be from approximately 8° to approximately 16°.Each relief face in each first set of cutting teeth may be disposed at afirst relief angle relative to a line tangent to the periphery of theblade body and each relief face in each second set of cutting teeth maybe disposed at a second rake angle relative to a line tangent to theperiphery of the blade body, the second relief angle less than the firstrelief angle. Each first relief angle may be from approximately 16° toapproximately 20° and each second relief angle may be from approximately8° to approximately 14°. Each second bevel angle may be less than eachfirst bevel angle, each second rake angle may be less than each firstrake angle, and each second relief angle may be less than each firstrelief angle.

The relief faces of each first set of cutting teeth may be beveledtoward one of the first side face and the second side face in analternating top bevel (ATB) pattern at a first top bevel angle and therelief faces of each second set of cutting teeth may be beveled towardone of the first side face and the second side face in an alternatingtop bevel (ATB) pattern at a second top bevel angle that is less thanthe first top bevel angle. Each first top bevel angle may be fromapproximately 16° to approximately 22° and each second top bevel anglemay be from approximately 8° to approximately 14°. Each second set ofteeth further may include a raker tooth. Each raker tooth may have therelief face unbeveled toward the first side face and the second sideface such that each second set of teeth are arranged in an alternatingtop bevel plus raker (ATB+R) pattern. The raker tooth may have a heightapproximately equal to or less than a height of each of the beveledteeth in the second set of teeth.

The relief faces of each first set of cutting teeth may be beveledtoward one of the first side face and the second side face in analternating top bevel (ATB) pattern at a first top bevel angle, and eachsecond set of cutting teeth may be a raker tooth. The relief face ofeach second set of cutting teeth may be unbeveled, may have a flat topface and beveled corner faces, or may be roof shaped. Each cutting toothmay include a carbide, cermet, polycrystalline diamond (PCD) or highspeed steel (HSS) cutting insert. Each first set of teeth and eachsecond set of teeth immediately following the first set of teeth in adirection opposite a cutting direction of the saw blade may beconfigured such that, if one tooth in the first set of teeth breaks, thechip load in the immediately following second set of teeth increases byless than 45%.

In another aspect, a circular saw blade includes a generally circularblade body having a first side face and an opposite second side face, aplurality of cutting tooth holders coupled to a periphery of the bladebody, a plurality of gullets, and a plurality of cutting teeth. Eachgullet is disposed between two adjacent cutting tooth holders. Eachcutting tooth is supported by one of the cutting tooth holders and has arake face facing toward an adjacent gullet and extending transverse tothe first and second side faces, a relief face extending from the rakeface toward the tooth holder that is supporting the cutting tooth andextending transverse to the first and second side faces, and a cuttingedge at a junction between the rake face and a relief face and extendingtransverse to the first and second side faces. The cutting teethrepeatedly alternate between a first set of cutting teeth and a secondset of cutting teeth immediately following the first set of cuttingteeth in a direction opposite a cutting direction of the saw bladearound the periphery of the blade body. Each first set of cutting teethincludes at least two efficient cutting teeth. Each second set ofcutting teeth comprising at least one robust cutting tooth. Each firstset of teeth and each second set of teeth are configured such that, ifone tooth in the first set of teeth breaks, the chip load in theimmediately following second set of teeth increases by less than 45%.

Implementations of this aspect may include one or more of the followingfeatures. The first set of teeth and the second set of teeth may beconfigured so that, prior to any teeth breaking, the second set of teethreceive a greater percentage of a total chip load on the plurality ofteeth than the first set of teeth. The first set of teeth may receiveapproximately 5% to 45% of the total chip load. The second set of teethreceive approximately 55% to 95% of the total chip load. Each rake facein each first set of cutting teeth may be disposed at a first rake anglerelative to a radius of the blade body and each rake face in each secondset of cutting teeth may be disposed at a second rake angle relative toa radius of the blade body, the second rake angle less than the firstrake angle. Each first rake angle may be from approximately 16° toapproximately 22° and each second rake angle may be from approximately8° to approximately 16°. Each relief face in each first set of cuttingteeth may be disposed at a first relief angle relative to a line tangentto the periphery of the blade body and each relief face in each secondset of cutting teeth may be disposed at a second rake angle relative toa line tangent to the periphery of the blade body, the second reliefangle less than the first relief angle. Each first relief angle may befrom approximately 16° to approximately 20° and each second relief anglemay be from approximately 8° to approximately 14°. Each second bevelangle may be less than each first bevel angle, each second rake anglemay be less than each first rake angle, and each second relief angle maybe less than each first relief angle.

The relief faces of each first set of cutting teeth may be beveledtoward one of the first side face and the second side face in analternating top bevel (ATB) pattern at a first top bevel angle and therelief faces of each second set of cutting teeth may be beveled towardone of the first side face and the second side face in an alternatingtop bevel (ATB) pattern at a second top bevel angle that is less thanthe first top bevel angle. Each first top bevel angle may be fromapproximately 16° to approximately 22° and each second top bevel anglemay be from approximately 8° to approximately 14°. Each second set ofteeth further may include a raker tooth. Each raker tooth may have therelief face unbeveled toward the first side face and the second sideface such that each second set of teeth are arranged in an alternatingtop bevel plus raker (ATB+R) pattern. The raker tooth may have a heightapproximately equal to or less than a height of each of the beveledteeth in the second set of teeth.

The relief faces of each first set of cutting teeth may be beveledtoward one of the first side face and the second side face in analternating top bevel (ATB) pattern at a first top bevel angle, and eachsecond set of cutting teeth may be a raker tooth. The relief face ofeach second set of cutting teeth may be unbeveled, may have a flat topface and beveled corner faces, or may be roof shaped. Each cutting toothmay include a carbide, cermet, polycrystalline diamond (PCD) or highspeed steel (HSS) cutting insert.

In another aspect, a circular saw blade includes a generally circularblade body having a first side face and an opposite second side face, aplurality of cutting tooth holders coupled to a periphery of the bladebody, a plurality of gullets, and a plurality of cutting teeth. Eachgullet is disposed between two adjacent cutting tooth holders. Eachcutting tooth is supported by one of the cutting tooth holders and has arake face facing toward an adjacent gullet and extending transverse tothe first and second side faces, a relief face extending from the rakeface toward the tooth holder that is supporting the cutting tooth andextending transverse to the first and second side faces, and a cuttingedge at a junction between the rake face and a relief face and extendingtransverse to the first and second side faces. The cutting teethalternate between at least one first set of cutting teeth and at leastone second set of cutting teeth around the periphery of the blade body.Each first set of cutting teeth includes at least two efficient cuttingteeth, each having the relief face beveled toward one of the first sideface and the second side face in an alternating top bevel (ATB) patternat a first top bevel angle, the rake face disposed at a first rake anglerelative to a radius of the blade body, and the relief face disposed ata first relief angle relative a line tangent to the periphery of theblade body. Each second set of cutting teeth includes at least onerobust raker cutting tooth, each having the rake face disposed at asecond rake angle relative to a radius of the blade body, and the reliefface disposed at a second relief angle relative a line tangent to theperiphery of the blade body. At least one out of the following twoconditions are satisfied: (a) each second rake angle is less than eachfirst rake angle, and (b) each second relief angle is less than eachfirst relief angle.

Implementations of this aspect may include one or more of the followingfeatures. If only one of the two conditions are satisfied, then one ofthe following additional conditions may be also satisfied: (a) eachsecond rake angle is approximately equal to each first rake angle; and(b) each second relief angle is approximately equal to each first reliefangle. Alternatively, each of the two conditions may be satisfied. Eachsecond bevel angle may be approximately equal to each first bevel angleand each second rake angle may be less than or equal to each first rakeangle. Each first rake angle may be from approximately 17° toapproximately 21° and each second rake angle may be from approximately12° to approximately 17°. Each first relief angle may be fromapproximately 12° to approximately 18° and each second relief angle maybe from approximately 10° to approximately 16°.

Each cutting tooth may include a carbide, cermet, polycrystallinediamond (PCD) or high speed steel (HSS) cutting insert. The first set ofteeth and the second set of teeth may be configured so that the secondset of teeth receive a greater percentage of a total chip load on theplurality of teeth than the first set of teeth. The first set of teethmay receive approximately less than 50% of the total chip load. Thesecond set of teeth receive approximately greater than 50% of the totalchip load. Each first set of teeth and each second set of teethimmediately following the first set of teeth in a direction opposite acutting direction of the saw blade may be configured such that, if onetooth in the first set of teeth breaks, the chip load in the immediatelyfollowing second set of teeth increases by less than 45%. The reliefface of each second set of cutting teeth may be unbeveled, may have aflat top face and beveled corner faces, or may be roof shaped.

Advantages may include one or more of the following. Alternating betweensets of efficient teeth and robust teeth creates a blade design wherethe efficient teeth can increase chip clearance, as they can have rakeangles, relief angles, and/or top bevel angles that are larger than whatwould be typically expected on a circular saw blade. This can be donebecause the robust teeth with smaller rake angles, relief angles, and/ortop bevel angles can withstand greater impact loads and inhibitpropagation of broken teeth around the periphery of the saw blade. Thisunexpectedly results in dramatic improvements in both wear life anddurability of the saw blade. These and other advantages and featureswill be apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an existing circular saw blade.

FIG. 2 is a close up view of a portion 2 of the saw blade of FIG. 1.

FIG. 3A is a cross-sectional view of the saw blade of FIG. 1 taken alongline 3A-3A.

FIG. 3B is a cross-sectional view of the saw blade of FIG. 1 taken alongline 3B-3B.

FIG. 4 is a side view of an embodiment of a circular saw blade accordingto this patent application.

FIG. 5 is a close up view of a portion 102 of the saw blade of FIG. 4.

FIGS. 6A and 6B are cross-sectional views taken along lines 6A-6A and6B-6B in FIG. 5.

FIGS. 7A and 7B are cross-sectional views taken along lines 7A-7A and7B-7B in FIG. 5.

FIGS. 8A and 8B are schematic chip model diagrams of the cutting teethof the saw blade of FIG. 1.

FIGS. 9A and 9B are schematic chip model diagrams of the cutting teethof a first embodiment of the saw blade of FIG. 4.

FIGS. 10A and 10B are schematic chip model diagrams of the cutting teethof a second embodiment of the saw blade of FIG. 4.

FIG. 11 is a chart illustrating results of life tests of threeembodiments of the saw blade of FIG. 4 in particle board.

FIG. 12 is a chart illustrating results of durability tests of threeembodiments of the saw blade of FIG. 4 in nail embedded wood.

FIG. 13 is a chart illustrating results of durability tests of threeembodiments of the saw blade of FIG. 4 in pine with lag bolts.

FIG. 14 is a side view of another embodiment of a circular saw bladeaccording to this patent application.

FIG. 15 is a close up view of a portion 202 of the saw blade of FIG. 14.

FIGS. 16A and 16B are cross-sectional views taken along lines 16A-16Aand 16B-16B in

FIG. 15.

FIGS. 17A, 17B, and 17C are cross-sectional views taken along lines17A-17A, 17B-17B, and 17C-17C in FIG. 15.

FIG. 18 is a side view of another embodiment of a circular saw bladeaccording to this patent application.

FIG. 19 is a close up view of a portion 302 of the saw blade of FIG. 18.

FIGS. 20 and 21 are cross-sectional views taken along lines 20-20 and21-21 in FIG. 18.

FIGS. 22A, 22B, and 22C are cross-sectional views taken along lines22A-22A, 22B-22B, and 22C-22C in FIG. 18.

FIGS. 23A and 23B are schematic chip model diagrams of the cutting teethof the saw blade of FIG. 18.

FIG. 24 is a close up view of a portion of another embodiment of a sawblade according to this patent application.

FIGS. 25A, 25B, and 25C are cross-sectional views of a firstimplementation of the saw blade of FIG. 24, taken along lines A-A, B-B,and C-C.

FIGS. 26A and 26B are schematic chip model diagrams of the cutting teethof the saw blade of FIGS. 25A-25C.

FIGS. 27A, 27B, and 27C are cross-sectional views of a secondimplementation of the saw blade of FIG. 24, taken along lines A-A, B-B,and C-C.

FIGS. 28A and 28B are schematic chip model diagrams of the cutting teethof the saw blade of FIGS. 27A-27C.

FIGS. 29A, 29B, and 29C are cross-sectional views of a thirdimplementation of the saw blade of FIG. 24, taken along lines A-A, B-B,and C-C.

FIGS. 30A and 30B are schematic chip model diagrams of the cutting teethof the saw blade of FIGS. 29A-29C.

DETAILED DESCRIPTION

Referring to FIGS. 4-7B, in an embodiment, a circular saw blade 110includes a generally circular blade body 112 having a first side face114 and an opposite second side face 116. A plurality of cutting toothholders 118 are coupled to a periphery 120 of the blade body 112. Aroundthe periphery 120 are a plurality of gullets 122, each disposed betweentwo adjacent cutting tooth holders 118. Each cutting tooth holder 118supports one of a plurality of cutting teeth 124. Each tooth 124 may begenerally prismatic in shape. The cutting teeth 124 alternate betweenfirst sets of cutting teeth 125A and second sets of cutting teeth 125Baround the periphery of the blade body. The cutting teeth 124 can becomposed of a harder material than the blade body, such as one or moreof carbide, cermet, polycrystalline diamond (PCD) or high speed steel(HSS).

Each first set of cutting teeth 125A comprises at least two (e.g., apair) of efficient cutting teeth 124A. Each efficient cutting tooth 124Ahas a first rake face 126A disposed at a first rake angle α1 relative toa radius R of the blade body and a first relief face 128A disposed at afirst relief angle β1 relative a line T1 tangent to a circumference C ofthe saw blade 110. In addition, the first cutting teeth 124A alternatebetween a left beveled cutting tooth 124A-L with a left top beveledrelief face 128A-L and a right beveled cutting tooth 124A-R a right topbeveled relief face 128A-R in an alternating top bevel (ATB) pattern.The relief faces 128A-L and 128A-R are beveled at a first top bevelangle γ1.

Each second set of cutting teeth 125B comprises at least two (e.g., apair) of robust cutting teeth 124B. Each robust cutting tooth 124B has afirst rake face 126B disposed at a second rake angle α1 relative to aradius R of the blade body and a first relief face 128B disposed at asecond relief angle β2 relative a line T2 tangent to the circumference Cof the saw blade 110. In addition, the second teeth 124B alternatebetween a left beveled tooth 124B-L with a left top beveled relief face128B-L and a right beveled tooth 124B-R with a right top beveled reliefface 128B-R in an alternating top bevel (ATB) pattern. The relief faces128B-L and 128B-R are beveled at a second top bevel angle γ2.

At least two out of the following three conditions are satisfied: (a)each second bevel angle γ2 is less than each first bevel angle γ1; (b)each second rake angle α2 is less than each first rake angle α1, and (c)each second relief angle β2 is less than each first relief angle β1. Forexample, at least two of the following three conditions may besatisfied: (a) each first top bevel angle γ1 may be from approximately16° to approximately 22° (e.g., approximately 18°) and each second topbevel angle γ2 may be from approximately 8° to approximately 14° (e.g.,approximately 13°); (b) each first rake angle α1 may be fromapproximately 16° to approximately 22° (e.g., approximately 20°), andeach second rake angle α2 may be from approximately 8° to approximately16° (e.g., approximately 12°); and (c) each first relief angle β1 may befrom approximately 16° to approximately 20° (e.g., approximately 16°)and each second rake angle β2 may be from approximately 8° toapproximately 14° (e.g., approximately) 10°. Note that in otherembodiments, all three of these conditions may be satisfied.

If only two of the aforementioned three conditions are satisfied, thenone of the following three conditions also may be satisfied: (a) eachsecond bevel angle γ2 may be approximately equal to the first bevelangle γ1; (b) each second rake angle α2 may be approximately equal toeach first rake angle α1; and (c) each second relief angle β2 may beapproximately equal to each first relief angle β1. For example, one ofthe following three conditions may be satisfied: (a) each first topbevel angle γ1 may be from approximately 8° to approximately 22° (e.g.,approximately 16°); (b) each first rake angle α1 and each second rakeangle α2 may be from approximately 8° to approximately 22° (e.g.,approximately 15°); and (c) each first relief angle β1 and each secondrake angle β2 may be from approximately 8° to approximately 20° (e.g.,approximately 16°).

The following Table 1 shows four example embodiments of circular sawblades in accordance with this disclosure:

TABLE 1 Embod- Embod- Embod- Embod- iment 1 iment 2 iment 3 iment 4First rake 20° 15° 20° 20° angle α1 Second rake 12° 15° 12° 12° angle α2First relief 16° 16° 16° 16° angle β1 Second relief 16° 10° 10° 10°angle β2 First top bevel 18° 20° 18° 16° angle γ1 Second top 13° 10° 13°16° bevel angle γ2

In each of these embodiments, the rake angles, relief angles, and topbevel angles on the efficient teeth 124A makes these teeth more acuteand aggressive, configuring these teeth to provide increased life formore efficient cutting through a workpiece. In contrast, the rakeangles, relief angles, and top bevel angles on the robust teeth 124Bmakes these teeth more obtuse and blunt, configuring these teeth to haveincreased durability with less chipping and breaking of these teeth whencutting abrasive materials such as wood with embedded nails.

Referring also to FIGS. 8A-10B, schematic illustrations of the chiploads on circular saw blades illustrate how the saw blades of thepresent disclosure mitigate and reduce the cascading effect of a toothbreakage in the saw blade. These figures schematically illustrate thesurface area upon which each tooth receives an impact force when cuttinga workpiece. The surface area is proportional to the amount of forcereceived by each tooth. Thus, a larger surface area receives a greaterforce than a smaller surface area.

FIGS. 8A-8B schematically illustrates the impacted surface area of theteeth in an existing saw blade, such as the one illustrated in FIGS.1-3B. As shown in FIG. 8A, because each tooth 24 has the same rakeangle, relief angle, and alternating top bevel angle, initially eachtooth has substantially the same surface area exposed to impact andreceives substantially equal shares of the impact force. For example,when using a 24-tooth 1.5 mm kerf circular saw blade with a 16°alternating top bevel, operating at 5000 rpm with a 7.5 ft./min. feedrate, the consecutive left top beveled teeth 24A-L, 24B-L and right topbeveled teeth 24A-R, 24B-R each has an exposed surface area ofapproximately 0.080 mm². As shown in FIG. 8B, if the first right beveledtooth 24A-R breaks, then the first left beveled tooth 24A-L and thesecond right beveled tooth 24B-R each have a larger exposed surface area(e.g., approximately 0.097 mm² and 0.143 mm², respectively). Thus, theimpact force on the first left beveled tooth 24A-L increases (e.g., byapproximately 21%) and the impact force on the second right beveledtooth 24B-R increases (e.g., by approximately 79%). The large (e.g.,greater than 50%) increase in the impact force on the second rightbeveled tooth 24B-R is much larger than that tooth is designed tohandle, and often will lead to breakage of that tooth. This, in turn,often leads to breakage of the next right beveled tooth, and so on.Thus, one broken tooth may cause a cascading series of broken teeth,resulting in premature and catastrophic failure of the saw blade.

In contrast, FIGS. 9A-9B and 10A-10B schematically illustrate thesurface area and impact loads on circular saw blades in accordance withEmbodiment 1 and Embodiment 2, respectively, of the saw blade shown inFIGS. 4-7B. As shown in FIGS. 9A and 10A, initially, the exposed surfacearea of the efficient teeth 124A-L, 124A-R is less than the exposedsurface area of the robust teeth 124B-L, 124B-R. This is donepurposefully because the robust teeth 124B-L, 124B-R are more able towithstand impact forces. For example, as shown in FIG. 9A, a circularsaw blade in accordance with Embodiment 1 that generates a chipthickness of approximately 0.05 mm, has an exposed surface area of theleft and right top beveled efficient teeth 124A-R, 124A-L ofapproximately 0.051 mm² and 0.049 mm², respectively, and an exposedsurface area of the left and right top beveled robust teeth 124B-L,124B-R of approximately 0.122 mm² and 0.099 mm², respectively. Thus, theefficient teeth 124A-L, 124A-R and the robust teeth 124B-L, 124B-Rreceive approximately 31% and 69% of the impact load, respectively. Inanother example, as shown in FIG. 10A, a circular saw blade inaccordance with Embodiment 2 that generates a chip thickness ofapproximately 0.05 mm, has an exposed surface area of the left and righttop beveled efficient teeth 124-R, 124-L of approximately 0.027 mm² and0.027 mm², respectively, and an exposed surface area of the left andright top beveled robust teeth 124B-R, 124B-L of approximately 0.107 mm²and 0.160 mm², respectively. Thus, the efficient teeth 124A-L, 124A-Rand the robust teeth 124B-L, 124B-R receive approximately 17% and 83% ofthe impact load, respectively.

As shown in FIGS. 9B and 10B, if one of the efficient teeth breaks, theexposed surface area of the following robust teeth increases, but by amuch smaller percentage than in existing saw blades. For example, asshown in FIG. 9B, in the design of Embodiment 1, if a right top beveledefficient tooth 124A-R breaks, the exposed surface areas of the left andright top beveled robust teeth 124B-R, 124B-L increase (e.g., toapproximately 0.138 mm² and 0.134 mm², respectively). Thus, the impactforce on the right top beveled robust tooth 124B-R increases (e.g., byapproximately 39%) and the impact force on the left top beveled robusttooth 124B-L increases (e.g., by approximately 10%). Similarly, as shownin FIG. 10B, in the design of Embodiment 2, if a right top beveledefficient tooth 124A-R breaks, the exposed surface areas of the rightand left top beveled robust teeth 124B-R, 124B-L increase (e.g., toapproximately 0.132 mm² and 0.162 mm², respectively). Thus, the impactforce on the right top beveled robust tooth 124B-R increases (e.g., byapproximately 23%) and the impact force on the left top beveled robusttooth 124B-L increases (e.g., by approximately 1%). In both cases, theincreased forces on the robust teeth are sufficiently low (e.g., lessthan a 45% increase) such that the robust teeth can handle the increasedforce, which inhibits cascading breakages of teeth around the peripheryof the saw blade.

The saw blades described above with respect to FIGS. 4-10B unexpectedlyhave dramatic increases in both life and durability. It was expected tohave an increase in durability based on a theory that replacing someefficient teeth with robust teeth would reduce propagation of toothfractures around the saw blade. It was also expected that replacing someefficient teeth with robust teeth would lead to a reduction in lifebased on the theory that there are fewer efficient teeth to removematerial from the workpiece. However, unexpectedly, the alternatingpattern of efficient teeth and robust teeth described above resulted insignificant improvements in both durability and life.

Referring to FIG. 11, samples of circular saw blades according toEmbodiments 1, 2, and 3 described above were compared in a life test tothree leading circular saw blades that are considered the best on themarket for a combination of life and durability. The saw blades weretested using a powered circular saw coupled to an automatic rig to cutstacks of two sheets of particle board. The rig senses the amount ofcutting force. The blade is considered to have reached its end of lifewhen the cutting force exceeds 6 pounds. The total length of particleboard cut determines which saw blades have the longest life. As shown inFIG. 11, the three existing circular saw blades cut an average ofapproximately 375 to 425 feet of particle board. The saw blade ofEmbodiment 1 of FIG. 4 cut an average of approximately 650 feet (animprovement of approximately 53% to approximately 73%). The saw blade ofEmbodiment 2 of FIG. 4 cut an average of approximately 1375 feet (animprovement of approximately 223% to approximately 267%), and Embodiment3 cut an average of approximately 1300 feet (an improvement ofapproximately 206% to approximately 247%). Thus, each of the embodimentsof the saw blade of FIG. 4 demonstrated dramatic and unexpectedimprovements in life.

Referring to FIG. 12, samples of circular saw blades according toEmbodiments 1, 2, and 3 described above were compared to the same threeleading circular saw blades in a durability test in nail embedded wood.This test was performed in 1½ inch thick pine embedded with 0.131 inchdiameter stainless steel nails to determine the number of nails cutuntil the blade fails, with a higher number indicating greaterdurability. As shown in FIG. 12, three existing circular saw blades cutan average of approximately 65 nails, 125 nails, and 140 nails,respectively. The saw blade of Embodiment 1 cut an average ofapproximately 225 nails (an improvement of approximately 61% toapproximately 246%). The saw blade of Embodiment 2 cut an average ofapproximately 140 nails (an improvement of approximately 0% toapproximately 115%). The saw blade of Embodiment 3 cut an average ofapproximately 180 nails (an improvement of approximately 28% toapproximately 180%). Thus, each of the embodiments of the saw blade ofFIG. 4 demonstrated dramatic improvements in durability.

Referring to FIG. 13, samples of circular saw blades according toEmbodiments 1, 2, and 3 described above were compared to the threeleading circular saw blades in a durability test in 1½ inch thick by 30inch-long pieces of pine embedded with ¼″ lag bolts. The saw blades wereused to cut the workpiece until it took more than 20 seconds to make acut, with a higher number of complete cuts indicating greaterdurability. As shown in FIG. 13, the three existing circular saw bladescompleted an average of approximately 4 cuts, 2.5 cuts, and 3 cuts,respectively. The saw blade of Embodiment 1 completed an average ofapproximately 7.5 cuts (an improvement of approximately 88% toapproximately 200%). The saw blade of Embodiment 2 completed an averageof approximately 8 cuts (an improvement of approximately 100% toapproximately 220%). The saw blade of Embodiment 3 completed an averageof approximately 8.5 cuts (an improvement of approximately 112% toapproximately 240%). Thus, this test further demonstrates that each ofthe embodiments of FIG. 4 exhibited dramatic improvements in durability.

Referring to FIGS. 14-17C, in another embodiment, a circular saw blade210 includes a generally circular blade body 212 having a first sideface 214 and an opposite second side face 216. A plurality of cuttingtooth holders 218 are coupled to a periphery 220 of the blade body 212.Around the periphery 220 are a plurality of gullets 222, each disposedbetween two adjacent cutting tooth holders 218. Each cutting toothholder 218 supports one of a plurality of cutting teeth 224. Each tooth224 may be generally prismatic in shape. The cutting teeth 224 alternatebetween first sets of cutting teeth 225A and second sets of cuttingteeth 225B around the periphery of the blade body. The saw blade 210differs from the saw blade 110 in that each second set of cutting teeth225B additionally includes a robust tooth 224B-U that is an unbeveled orraker tooth.

Each first set of cutting teeth 225A comprises at least two (e.g., apair) of efficient cutting teeth 224A. Each efficient cutting tooth 224Ahas a first rake face 226A disposed at a first rake angle α1 relative toa radius R of the blade body and a first relief face 228A disposed at afirst relief angle β1 relative a line T1 tangent to a circumference C ofthe saw blade 210. In addition, the first cutting teeth 224A alternatebetween a left beveled cutting tooth 224A-L with a left top beveledrelief face 228A-L and a right beveled cutting tooth 224A-R with a righttop beveled relief face 228A-R in an alternating top bevel (ATB)pattern. The relief faces 228A-L and 228B-R are beveled at a first topbevel angle γ1.

Each second set of cutting teeth 225B comprises at least three (e.g.,three) robust cutting teeth 224B. Each robust cutting tooth 224B has afirst rake face 226B disposed at a second rake angle α2 relative to aradius R of the blade body and a second relief face 228B disposed at asecond relief angle β2 relative a line T2 tangent to the circumference Cof the saw blade 210. In addition, the second teeth 224B include a leftbeveled tooth 224B-L with a left top beveled relief face 228B-L, a rightbeveled tooth 224B-R with a right top beveled relief face 228B-R, andthe unbeveled (or raker) tooth 224B-U with an unbeveled relief face228B-U, arranged in an alternating top bevel+raker (ATB+R) pattern. Theleft and right top beveled relief faces 228B-L and 228B-R are beveled ata second top bevel angle γ2.

At least two out of the following three conditions are satisfied: (a)each second bevel angle γ2 is less than each first bevel angle γ1; (b)each second rake angle α2 is less than each first rake angle α1, and (c)each second relief angle β2 is less than each first relief angle β1. Forexample, at least two of the following three conditions may besatisfied: (a) each first top bevel angle γ1 may be from approximately16° to approximately 22° (e.g., approximately 18°) and each second topbevel angle γ2 may be from approximately 8° to approximately 14° (e.g.,approximately 13°); (b) each first rake angle α1 may be fromapproximately 16° to approximately 22° (e.g., approximately 20°), andeach second rake angle α2 may be from approximately 8° to approximately16° (e.g., approximately 12°); and (c) each first relief angle β1 may befrom approximately 16° to approximately 20° (e.g., approximately 16°)and each second rake angle β2 may be from approximately 8° toapproximately 14° (e.g., approximately) 10°. Note that in otherembodiments, all three of these conditions may be satisfied.

If only two of the aforementioned three conditions are satisfied, thenone of the following additional conditions also may be satisfied: (a)each second bevel angle γ2 may be approximately equal to the first bevelangle γ1; (b) each second rake angle α2 may be approximately equal toeach first rake angle α1; and (c) each second relief angle β2 may beapproximately equal to each first relief angle β1. For example, one ofthe following three conditions may be satisfied: (a) each first topbevel angle γ1 may be from approximately 8° to approximately 22° (e.g.,approximately 16°); (b) each first rake angle α1 and each second rakeangle α2 may be from approximately 8° to approximately 22° (e.g.,approximately 15°); and (c) each first relief angle β1 and each secondrake angle β2 may be from approximately 8° to approximately 20° (e.g.,approximately 16°). The addition of the unbeveled robust tooth 224B-Uhelps further reduce the impact force on all teeth in the first andsecond sets, which further improves the durability of the saw blade.

Referring to FIGS. 18-22C, in another embodiment, a circular saw blade310 includes a generally circular blade body 312, a plurality of cuttingtooth holders 318 coupled to a periphery of the blade body 312, and aplurality of cutting teeth 324 supported by the tooth holders 318,similar to the blade body 212, tooth holders 218, and cutting teeth 224of the saw blade 210 of FIGS. 14-17C. Each tooth 324 may be generallyprismatic in shape. Like the saw blade 210, the cutting teeth 324 of sawblade 310 alternate between first sets of cutting teeth 325A and secondsets of cutting teeth 325B around the periphery of the blade body.

Each first set of cutting teeth 325A comprises at least two (e.g., apair) of efficient cutting teeth 324A. Each efficient cutting tooth 324Ahas a first rake face 326A disposed at a first rake angle α1 relative toa radius R of the blade body and a first relief face 328A disposed at afirst relief angle β1 relative a line T1 tangent to a circumference C ofthe blade body 312. In addition, the first cutting teeth 324A alternatebetween a left beveled cutting tooth 324A-L with a left top beveledrelief face 328A-L and a right beveled cutting tooth 324A-R with a righttop beveled relief face 328A-R in an alternating top bevel (ATB)pattern. The relief faces 328A-L and 328B-R are beveled at a first topbevel angle γ1.

Each second set of cutting teeth 325B comprises at least three (e.g.,three) robust cutting teeth 324B. Each robust cutting tooth 324B has afirst rake face 326B disposed at a second rake angle α2 relative to aradius R of the blade body and a second relief face 328B disposed at asecond relief angle β2 relative a line T2 tangent to the circumference Cof the saw blade 210. In addition, the second teeth 324B include a leftbeveled tooth 324B-L with a left top beveled relief face 328B-L, a rightbeveled tooth 324B-R with a right top beveled relief face 328B-R, andthe unbeveled (or raker) tooth 324B-U with an unbeveled relief face328B-U, arranged in an alternating top bevel+raker (ATB+R) pattern. Theleft and right top beveled relief faces 328B-L and 328B-R are beveled ata second top bevel angle γ2.

At least two out of the following three conditions are satisfied: (a)each second bevel angle γ2 is less than each first bevel angle γ1; (b)each second rake angle α2 is less than each first rake angle α1, and (c)each second relief angle β2 is less than each first relief angle β1. Forexample, at least two of the following three conditions may besatisfied: (a) each first top bevel angle γ1 may be from approximately16° to approximately 22° (e.g., approximately 18°) and each second topbevel angle γ2 may be from approximately 8° to approximately 14° (e.g.,approximately 13°); (b) each first rake angle α1 may be fromapproximately 16° to approximately 22° (e.g., approximately 20°), andeach second rake angle α2 may be from approximately 8° to approximately16° (e.g., approximately 12°); and (c) each first relief angle β1 may befrom approximately 16° to approximately 20° (e.g., approximately 16°)and each second rake angle β2 may be from approximately 8° toapproximately 14° (e.g., approximately) 10°. Note that in otherembodiments, all three of these conditions may be satisfied.

If only two of the aforementioned three conditions are satisfied, thenone of the following three conditions also may be satisfied: (a) eachsecond bevel angle γ2 may be approximately equal to the first bevelangle γ1; (b) each second rake angle α2 may be approximately equal toeach first rake angle α1; and (c) each second relief angle β2 may beapproximately equal to each first relief angle β1. For example, one ofthe following three conditions may be satisfied: (a) each first topbevel angle γ1 may be from approximately 8° to approximately 22° (e.g.,approximately 16°); (b) each first rake angle α1 and each second rakeangle α2 may be from approximately 8° to approximately 22° (e.g.,approximately 15°); and (c) each first relief angle β1 and each secondrake angle β2 may be from approximately 8° to approximately 20° (e.g.,approximately 16°).

The saw blade 320 differs from the saw blade 220 in that the unbeveledrobust tooth 324B-U is lowered by height ΔH1 (e.g., approximately 0.03mm to approximately 0.075 mm) from the saw circumference C. The lowerheight of unbeveled robust tooth 324B-U reduces the chip load onunbeveled robust tooth 324B-U and helps balance the chip load betweenthe top beveled robust teeth 324B-R and 324B-L. For example, loweringthe height on the unbeveled robust tooth 324B-U may reduce the chip loadon that tooth as compared to the chip load on the unbeveled robust tooth324B-U being approximately twice the chip thickness as that of the topbeveled robust teeth 324B-R and 324B-L without the height reduction. Inother embodiments, the unbeveled robust tooth may have a top face withshapes other than the flat top face shown in FIG. 22C, while stillachieving the benefits of reduced chip load described above.

FIGS. 23A-23B schematically illustrate the exposed surface area andimpact loads on the circular saw blade shown in FIGS. 19-22C. As shownin FIG. 23A, initially, prior to any tooth breakage, the total exposedsurface area of the efficient teeth 324A-L, 324A-R is less than thetotal exposed surface area of the robust teeth 324B-L, 324B-R, 324B-U.This is purposeful because the robust teeth are more able to withstandimpact loading. For example, in an embodiment of such a saw blade with a1.6 mm kerf and a chip thickness of approximately 0.05 mm, the exposedsurface areas of the right and left top beveled efficient teeth 324A-R,324A-L may be approximately 0.031 mm² and 0.014 mm², respectively, whilethe exposed surface area of the right top beveled, left top beveled, andunbeveled robust teeth 324B-R, 324B-L, 324B-U are approximately 0.106mm², 0.100 mm², and 0.149 mm², respectively. Thus, the efficient teeth324A and robust teeth 324B receive approximately 11% and 89% of theimpact load, respectively.

As shown in FIG. 23B, if one of the efficient teeth breaks, the exposedsurface area of the robust teeth increases, but by a much smallerpercentage than in existing saw blades. For example, if a right beveledefficient tooth 324A-R breaks, the exposed surface area of the followingright beveled robust tooth 324B-R increases to approximately 0.137 mm²,while the exposed surface area of the left beveled and unbeveled robustteeth 324B-L, 324B-U remain the same. Thus, the impact force on theright top beveled robust tooth 324B-R increases by only approximately29%. This increased force is sufficiently low (e.g., less than a 45%increase) such that the robust tooth can handle the increased force,which inhibits cascading breakages of teeth around the periphery of thesaw blade.

Referring to FIGS. 24-30B, in other embodiments, a circular saw blade410 includes a generally circular blade body 412 having a first sideface 414 and an opposite second side face 416. A plurality of cuttingtooth holders 418 are coupled to a periphery 420 of the blade body 412.Around the periphery 420 are a plurality of gullets 422, each disposedbetween two adjacent cutting tooth holders 418. Each cutting toothholder 418 supports one of a plurality of cutting teeth 424. Each tooth424 may be generally prismatic in shape. The cutting teeth 424 alternatebetween first sets of cutting teeth 425A and second sets of cuttingteeth 425B around the periphery of the blade body.

Each first set of cutting teeth 425A comprises at least two (e.g., apair) of efficient cutting teeth 424A. Each efficient cutting tooth 424Ahas a first rake face 426A disposed at a first rake angle α1 relative toa radius R of the blade body and a first relief face 428A disposed at afirst relief angle β1 relative a line T1 tangent to a circumference C ofthe saw blade 410. In addition, the first cutting teeth 424A alternatebetween a left beveled cutting tooth 424A-L with a left top beveledrelief face 428A-L and a right beveled cutting tooth 424A-R with a righttop beveled relief face 428A-R in an alternating top bevel (ATB)pattern. The relief faces 428A-L and 428B-R are beveled at a first topbevel angle γ1.

Each second set of cutting teeth 425B comprises at least one (e.g., onlyone) robust cutting tooth 424B, each being a raker tooth (i.e., nothaving an alternating top bevel that alternates between left and rightbeveled relief faces). Each robust raker cutting tooth 424B has a firstrake face 426B disposed at a second rake angle α2 relative to a radius Rof the blade body and a second relief face 428B disposed at a secondrelief angle β2 relative a line T2 tangent to the circumference C of thesaw blade 410. At least one out of the following two conditions aresatisfied: (a) each second rake angle α2 is less than each first rakeangle α1, and (b) each second relief angle β2 is less than each firstrelief angle β1. For example, at least one of the following twoconditions may be satisfied: (a) each first rake angle α1 may be fromapproximately 17° to approximately 21° (e.g., approximately 20°), andeach second rake angle α2 may be from approximately 12° to approximately18° (e.g., approximately 16°); and (b) each first relief angle β1 may befrom approximately 12° to approximately 18° (e.g., approximately 16° andeach second rake angle β2 may be from approximately 12° to approximately17° (e.g., approximately 12°). Note that in other embodiments, both ofthese conditions may be satisfied. Also, in yet other embodiments, eachsecond set of cutting teeth may include a plurality of the robust rakerteeth.

In a first implementation of this embodiment (as shown in FIGS.25A-25C), each second tooth 424B is a raker tooth 424B-U1 with a flat,unbeveled top relief face 428B-U1. In a second implementation of thisembodiment (as shown in FIGS. 27A-27C), each second tooth 424B is araker tooth 424B-U2 with a flat, unbeveled top relief face 428B-U2 andbeveled corner faces 429B-U2 beveled at a corner bevel angle θ2 (e.g.,approximately 7° to approximately 25°). In a third implementation ofthis embodiment (as shown in FIGS. 29A-29C), each second tooth 424B is araker tooth 424B-U3 with a roof shaped top relief face 428B-U3 withbeveled faces 429B-U3 beveled at a roof bevel angle θ3 (e.g.,approximately 6° to approximately 20°).

FIGS. 26A and 26B schematically illustrate the exposed surface area andimpact loads on the first implementation of this embodiment shown inFIGS. 25A-25C. As shown in FIG. 26A, initially, prior to any toothbreakage, the total exposed surface area of a pair of efficient teeth424A-L, 324A-R is less than or equal to the total exposed surface area afollowing robust tooth 424B-U1. For example, in an embodiment of such asaw blade with a 1.6 mm kerf, a chip thickness of approximately 0.05 mm,and a raker tooth edge approximately 0.10 mm below the circumferenceformed by the tips of the efficient teeth, the exposed surface areas ofeach left and right top beveled efficient teeth 424A-L, 424A-R may beapproximately 0.063 mm² and 0.045 mm², respectively, while the exposedsurface area of each raker robust tooth 324B-U1 is approximately 0.113mm². Thus, the efficient teeth 424A and robust teeth 424B receiveapproximately 45% and 55% of the impact load, respectively.

As shown in FIG. 26B, if one of the efficient teeth breaks, the exposedsurface area of the following robust tooth 424B-U1 increases, but by amuch smaller percentage than in existing saw blades. For example, if aleft beveled efficient tooth 424A-L breaks, the exposed surface area offollowing raker robust tooth 424B-U1 increases to 0.190 mm², i.e., anincrease of only approximately 45%. This increased force is sufficientlylow (e.g., an approximately 45% increase) such that the robust tooth canhandle the increased force, which inhibits cascading breakages of teetharound the periphery of the saw blade.

FIGS. 28A and 28B schematically illustrate the exposed surface area andimpact loads on the second implementation of this embodiment shown inFIGS. 27A-27C. As shown in FIG. 28A, initially, prior to any toothbreakage, the total exposed surface area of a pair of efficient teeth424A-L, 324A-R is greater than or equal to the total exposed surfacearea a following robust tooth 424B-U2. For example, in an embodiment ofsuch a saw blade with a 1.6 mm kerf and a chip thickness ofapproximately 0.05 mm, the exposed surface areas of each left and righttop beveled efficient teeth 424A-L, 424A-R may be approximately 0.064mm² and 0.073 mm², respectively, while the exposed surface area of eachraker robust tooth 324B-U1 is approximately 0.095 mm². Thus, theefficient teeth 424A and robust teeth 424B receive approximately 59% and41% of the impact load, respectively.

As shown in FIG. 28B, if one of the efficient teeth breaks, the exposedsurface area of the following robust tooth 424B-U2 increases, but by amuch smaller percentage than in existing saw blades. For example, if aright beveled efficient tooth 424A-R breaks, the exposed surface area offollowing raker robust tooth 424B-U2 increases to 0.135, i.e., anincrease of only approximately 42%. This increased force is sufficientlylow (e.g., also approximately 42% increase) such that the robust toothcan handle the increased force, which inhibits cascading breakages ofteeth around the periphery of the saw blade.

FIGS. 30A and 30B schematically illustrate the exposed surface area andimpact loads on the first implementation of this embodiment shown inFIGS. 29A-299C. As shown in FIG. 30A, initially, prior to any toothbreakage, the total exposed surface area of a pair of efficient teeth424A-L, 324A-R is approximately equal to the total exposed surface areaa following robust tooth 424B-U1. For example, in an embodiment of sucha saw blade with a 1.6 mm kerf and a chip thickness of approximately0.05 mm, the exposed surface areas of each left and right top beveledefficient teeth 424A-L, 424A-R may be approximately 0.054 mm² and 0.066mm², respectively, while the exposed surface area of each raker robusttooth 324B-U3 is approximately 0.120 mm². Thus, the efficient teeth 424Aand robust teeth 424B each receive approximately 50% of the impact load,respectively.

As shown in FIG. 30B, if one of the efficient teeth breaks, the exposedsurface area of the following robust tooth 424B-U3 increases, but by amuch smaller percentage than in existing saw blades. For example, if aright beveled efficient tooth 424A-R breaks, the exposed surface area offollowing raker robust tooth 424B-U3 increases to 0.158, i.e., anincrease of approximately 32%. This increased force is sufficiently low(e.g., also approximately 32% increase) such that the robust tooth canhandle the increased force, which inhibits cascading breakages of teetharound the periphery of the saw blade.

Example embodiments have been provided so that this disclosure will bethorough, and to fully convey the scope to those who are skilled in theart. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Terms of degree such as “generally,” “substantially,” “approximately,”and “about” may be used herein when describing the relative positions,sizes, dimensions, or values of various elements, components, regions,layers and/or sections. These terms mean that such relative positions,sizes, dimensions, or values are within the defined range or comparison(e.g., equal or close to equal) with sufficient precision as would beunderstood by one of ordinary skill in the art in the context of thevarious elements, components, regions, layers and/or sections beingdescribed.

Numerous modifications may be made to the exemplary implementationsdescribed above. These and other implementations are within the scope ofthe following claims.

What is claimed is:
 1. A circular saw blade comprising: a generallycircular blade body having a first side face and an opposite second sideface; a plurality of cutting tooth holders coupled to a periphery of theblade body; a plurality of gullets, each gullet disposed between twoadjacent cutting tooth holders; a plurality of cutting teeth, eachcutting tooth supported by one of the cutting tooth holders and having arake face facing toward an adjacent gullet and extending transverse tothe first and second side faces, a relief face extending from the rakeface toward the tooth holder that is supporting the cutting tooth andextending transverse to the first and second side faces, and a cuttingedge at a junction between the rake face and a relief face and extendingtransverse to the first and second side faces, wherein the cutting teethalternate between at least one first set of cutting teeth and at leastone second set of cutting teeth around the periphery of the blade body,wherein each first set of cutting teeth comprise at least two efficientcutting teeth, each having the relief face beveled toward one of thefirst side face and the second side face in an alternating top bevelpattern at a first top bevel angle, the rake face disposed at a firstrake angle relative to a radius of the blade body, and the relief facedisposed at a first relief angle relative a line tangent to theperiphery of the blade body, wherein each second set of cutting teethcomprise at least two robust cutting teeth, each having with the relieffaces beveled toward one of the first side face and the second side facein an alternating top bevel pattern at a second top bevel angle, therake face disposed at a second rake angle relative to a radius of theblade body, and the relief face disposed at a second relief anglerelative a line tangent to the periphery of the blade body, and whereinat least two out of the following three conditions are satisfied: (a)each second bevel angle is less than each first bevel angle; (b) eachsecond rake angle is less than each first rake angle, and (c) eachsecond relief angle is less than each first relief angle.
 2. Thecircular saw blade of claim 1, wherein only two of the three conditionsare satisfied, and one of the following additional conditions is alsosatisfied: (a) each second bevel angle is approximately equal to thefirst bevel angle; (b) each second rake angle is approximately equal toeach first rake angle; and (c) each second relief angle is approximatelyequal to each first relief angle.
 3. The circular saw blade of claim 1,wherein all of the three conditions are satisfied.
 4. The circular sawblade of claim 1, wherein each second bevel angle is less than eachfirst bevel angle, each second rake angle is less than each first rakeangle, and each second relief angle is approximately equal to each firstrelief angle.
 5. The circular saw blade of claim 1, wherein each secondbevel angle is approximately equal to each first bevel angle, eachsecond rake angle is less than each first rake angle, and each secondrelief angle is less than each first relief angle.
 6. The circular sawblade of claim 1, wherein each second bevel angle is less than eachfirst bevel angle, each second rake angle is approximately equal to eachfirst rake angle, and each second relief angle is less than each firstrelief angle.
 7. The circular saw blade of claim 1, wherein each firstrake angle is from approximately 16° to approximately 22° and eachsecond rake angle is from approximately 8° to approximately 16°.
 8. Thecircular saw blade of claim 1, wherein each first relief angle is fromapproximately 16° to approximately 20° and each second rake angle isfrom approximately 8° to approximately 14°.
 9. The circular saw blade ofclaim 1, wherein each first top bevel angle is from approximately 16° toapproximately 22° and each second top bevel angle is from approximately8° to approximately 14°.
 10. The circular saw blade of claim 1, whereineach cutting tooth comprises a cutting insert composed of a hardermaterial than the blade body.
 11. The circular saw blade of claim 1,wherein the first set of teeth and the second set of teeth areconfigured so that the second set of teeth receive a greater percentageof a total chip load on the plurality of teeth than the first set ofteeth.
 12. The circular saw blade of claim 1, wherein each second set ofteeth further includes a raker tooth, each raker tooth having the reliefface unbeveled toward the first side face and the second side face, therake face disposed at the second rake angle relative to a radius of theblade body, and the relief face disposed at the second relief anglerelative a line tangent to the periphery of the blade body.
 13. Thecircular saw blade of claim 1, wherein each first set of teeth and eachsecond set of teeth immediately following the first set of teeth in adirection opposite a cutting direction of the saw blade are configuredsuch that, if one tooth in the first set of teeth breaks, the chip loadin the immediately following second set of teeth increases by less than45%.
 14. A circular saw blade comprising: a generally circular bladebody having a first side face and an opposite second side face; aplurality of cutting tooth holders coupled to a periphery of the bladebody; a plurality of gullets, each gullet disposed between two adjacentcutting tooth holders; a plurality of cutting teeth, each cutting toothsupported by one of the cutting tooth holders and having a rake facefacing toward an adjacent gullet and extending transverse to the firstand second side faces, a relief face extending from the rake face towardthe tooth holder that is supporting the cutting tooth and extendingtransverse to the first and second side faces, and a cutting edge at ajunction between the rake face and a relief face and extendingtransverse to the first and second side faces, the cutting teethalternating between at least one first set of cutting teeth and at leastone second set of cutting teeth around the periphery of the blade body,each first set of cutting teeth comprising at least two efficientcutting teeth, each second set of cutting teeth comprising at least onerobust cutting tooth, wherein the first set of teeth and the second setof teeth are configured so that the second set of teeth receive agreater percentage of a total chip load on the plurality of teeth thanthe first set of teeth.
 15. The circular saw blade of claim 14, whereinthe first set of teeth receive approximately 5% to 45% of the total chipload.
 16. The circular saw blade of claim 15, wherein the second set ofteeth receive approximately 55% to 95% of the total chip load.
 17. Thecircular saw blade of claim 1, wherein each rake face in each first setof cutting teeth is disposed at a first rake angle relative to a radiusof the blade body and each rake face in each second set of cutting teethis disposed at a second rake angle relative to a radius of the bladebody, the second rake angle less than the first rake angle.
 18. Thecircular saw blade of claim 17, wherein each relief face in each firstset of cutting teeth is disposed at a first relief angle relative to aline tangent to the periphery of the blade body and each relief face ineach second set of cutting teeth is disposed at a second rake anglerelative to a line tangent to the periphery of the blade body, thesecond relief angle less than the first relief angle.
 19. The circularsaw blade of claim 18, wherein each second bevel angle is less than eachfirst bevel angle, each second rake angle is less than each first rakeangle, and each second relief angle is less than each first reliefangle.
 20. A circular saw blade comprising: a generally circular bladebody having a first side face and an opposite second side face; aplurality of cutting tooth holders coupled to a periphery of the bladebody; a plurality of gullets, each gullet disposed between two adjacentcutting tooth holders; a plurality of cutting teeth, each cutting toothsupported by one of the cutting tooth holders and having a rake facefacing toward an adjacent gullet and extending transverse to the firstand second side faces, a relief face extending from the rake face towardthe tooth holder that is supporting the cutting tooth and extendingtransverse to the first and second side faces, and a cutting edge at ajunction between the rake face and a relief face and extendingtransverse to the first and second side faces, the cutting teethrepeatedly alternating between a first set of cutting teeth and a secondset of cutting teeth immediately following the first set of cuttingteeth in a direction opposite a cutting direction of the saw bladearound the periphery of the blade body, each first set of cutting teethcomprising at least two efficient cutting teeth, each second set ofcutting teeth comprising at least one robust cutting tooth, wherein eachfirst set of teeth and each second set of teeth are configured suchthat, if one tooth in the first set of teeth breaks, the chip load inthe immediately following second set of teeth increases by less than45%.